It is known from German Patent Specifications 2,051,354 and 1,456,661 to feed wire, drawn off from a coil, intermittently through a straightening device by a selectable length, to cut off longitudinal elements and to feed the latter by means of a conveying device transversely to the push-in line to a horizontal magazine which consists of a plurality of chains which can be moved step-by-step and have receiving pockets for one longitudinal wire each. The longitudinal wires, by means of a transporting carriage, are lifted in groups out of the magazine acting as intermediate storage means and are conveyed transversely to the push-in line in front of a stationary delivery device of the welding machine and are delivered to the latter.
A disadvantage in this procedure is the inevitably horizontal and consequently bulky arrangement of the magazine, whose width has to correspond to at least the largest width of the grate to be manufactured. In addition, a relatively low operating speed results, caused by the slow filling of the magazine by means of the intermittently working straightening and cutting device and on account of the use of only one transporting carriage, which has to remain in the delivery position relative to the welding machine until all longitudinal wires have been worked by the welding machine. Furthermore, an infinitely adjustable spacing of the longitudinal wires is not possible.
German Patent Specification 2,319,003 (published Oct. 17, 1974) discloses a feeding mechanism in which a transporting device arranged horizontally and parallel to the welding machine and intended for longitudinal wires is formed by an endless, rotating transverse-conveying device provided with receiving members for the longitudinal wires. The longitudinal wires are conveyed into the receiving members by means of a straightening and cutting device arranged in front of the transverse-conveying device in the direction of the longitudinal wires and movable transversely to the direction of the longitudinal wires. In another embodiment, the longitudinal bars straightened and cut by means of the straightening and cutting device are first of all fed to a supply magazine and then pass via a singularizing device into a further magazine and from the latter into a channel. From this channel, the longitudinal bars are fed by means of a draw-in device to the receiving members of the transverse-conveying device Finally, in a further exemplary embodiment, the longitudinal wires are fed directly from the magazine into the receiving members of the transverse-conveying device.
A disadvantage in the first-mentioned embodiment is the fact that a transverse displacement of the feeding device, consisting of straightening and cutting devices as well as the corresponding feed mechanisms can only be realised by a considerably complex design; on the other hand, in a fixed feeding device, a passing movement of the transverse-conveying device for the purpose of loading with longitudinal wires can only be effected when the welding machine has removed all longitudinal wires from the transverse-conveying device.
The other two embodiments certainly enable round longitudinal wires to be lifted out of the transverse-conveying device and thus also enable the transverse-conveying device to pass directly after the longitudinal wires have been welded to the first cross wires. However, this is not possible in the case of longitudinal elements which are resistant to bending in the longitudinal direction, such as strip-shaped supporting bars disposed edgewise for gratings, since these supporting bars cannot be lifted or lowered in the direction of their narrow side without deforming or twisting.